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Abstract:

The first communication system is configured to determine whether or not
to provide information that instructs the UE 10 to connect to the second
communication system, based on a subscriber identifier allocated to the
UE 10. The subscriber identifier is configured to identify whether or not
the UE 10 is allowed to utilize the second communication system.

Claims:

1. A mobile communication system having a mobile communication terminal,
a first communication system, and a second communication system, wherein
the first communication system is configured to determine whether or not
to provide information that instructs the mobile communication terminal
to connect to the second communication system, based on a subscriber
identifier allocated to the mobile communication terminal, and The
subscriber identifier is configured to identify whether or not the mobile
communication terminal is allowed to utilize the second communication
system.

2. A radio control apparatus provided in a first communication system in
a mobile communication system having a mobile communication terminal, the
first communication system, and a second communication system, the radio
control apparatus comprising a determination unit configured to determine
whether or not to provide notification of information that instructs the
mobile communication terminal to connect to the second communication
system, based on a subscriber identifier allocated to the mobile
communication terminal, wherein the subscriber identifier is configured
to identify whether or not the mobile communication terminal is allowed
to utilize the second communication system.

3. A core network apparatus provided in a mobile communication system
having a mobile communication terminal, a first communication system, and
a second communication system, the core network apparatus comprising an
allocation unit configured to allocate a subscriber identifier to the
mobile communication terminal, the subscriber identifier being configured
to identify whether or not the mobile communication terminal is allowed
to utilize the second communication system.

4. A mobile communication terminal configured to perform communications
with a first communication system and a second communication system in a
mobile communication system having the first communication system and the
second communication system, the mobile communication terminal comprising
a transmission unit configured to configure a subscriber identifier to
identify whether or not the mobile communication terminal is allowed to
utilize the second communication system, and to transmit a radio signal
in which the subscriber identifier is set to the first communication
system.

5. A mobile communication terminal capable of performing communications
with a first communication system and a second communication system in a
mobile communication system having the first communication system and the
second communication system, the mobile communication terminal comprising
a setting unit configured that: the setting unit does not set information
indicating capability to support the second communication system in a
radio signal to be transmitted from the mobile communication terminal to
the first communication system, when the mobile communication terminal is
restricted from utilizing the second communication system; and the
setting unit sets the information indicating the capability to support
the second communication system in the radio signal to be transmitted
from the mobile communication terminal to the first communication system,
when the mobile communication system is not restricted from utilizing the
second communication system.

6. A mobile communication method for a mobile communication terminal to
perform communications with a first communication system and a second
communication system, the mobile communication method comprising a step
of causing the first communication system to determine whether or not to
provide information that instructs the mobile communication terminal to
connect to the second communication system, based on a subscriber
identifier allocated to the mobile communication terminal, wherein the
subscriber identifier is configured to identify whether or not the mobile
communication terminal is allowed to utilize the second communication
system.

Description:

TECHNICAL FIELD

[0001] The present invention relates to: a mobile communication system
including a first communication system and a second communication system;
a radio control apparatus, a core network apparatus, and a mobile
communication terminal which are provided in a mobile communication
system; as well as a mobile communication method which is used in a
mobile communication system.

BACKGROUND ART

[0002] The following procedure (RRC CONNECTION REJECT with redirection)
has been known as a procedure for a mobile communication terminal (UE) to
establish a connection from a first communication system (first RAT
(Radio Access Technology)) to a second communication system (second RAT)
in a mobile communication system (for example, non-patent document 1).

[0003] First, the mobile communication terminal transmits to the first
communication system a radio signal (RRC CONNECTION REQUEST) in which
information (pre-redirection info) indicating capability to support the
second communication system is set.

[0004] Secondly, in response to the radio signal (RRC CONNECTION REQUEST)
from the mobile communication terminal, the first communication system
transmits a radio signal (RRC CONNECTION REJECT) to instruct the mobile
communication terminal to connect to the second communication system
(redirection).

PRIOR ART DOCUMENTS

Non-Patent Document

[0005] Non-patent document 1: 3GPP TS25. 331 v9. 0. 0

SUMMARY OF THE INVENTION

[0006] However, even though the mobile communication terminal has the
capability to support the second communication system, it is possible
that the mobile communication terminal is not allowed to utilize the
second communication system, specifically, the mobile communication
terminal has no contract made to utilize the second communication system.
In such a case, the connection procedure of the mobile communication
terminal to the second communication system is rejected, and the mobile
communication terminal returns to the first communication system.
However, since the mobile communication terminal still has the capability
to support the second communication system, the mobile communication
terminal re-transmits the radio signal (RRC CONNECTION REQUEST) in which
the information (pre-redirection info) indicating the capability to
support the second communication system is set in the first communication
system.

[0007] Thus, the connection procedure to the second communication system
(second RAT) will be repeated (ping pong phenomenon) unless it is
considered whether or not the mobile communication terminal has a
contract made to utilize the second communication system.

[0008] Hence, the present invention has been made to solve the problem
described above, and an object of the present invention is to provide a
mobile communication system, a radio control apparatus, a core network
apparatus, a mobile communication terminal, and a mobile communication
method which can prevent repetition of a connection procedure to a second
communication system.

[0009] A mobile communication system according to the first feature has a
mobile communication terminal, a first communication system, and a second
communication system. The first communication system is configured to
determine whether or not to provide information that instructs the mobile
communication terminal to connect to the second communication system,
based on a subscriber identifier allocated to the mobile communication
terminal. The subscriber identifier is configured to identify whether or
not the mobile communication terminal is allowed to utilize the second
communication system.

[0010] A radio control apparatus according to the second feature is
provided in a first communication system in a mobile communication system
having a mobile communication terminal, the first communication system,
and a second communication system. The radio control apparatus comprising
a determination unit configured to determine whether or not to provide
information that instructs the mobile communication terminal to connect
to the second communication system, based on a subscriber identifier
allocated to the mobile communication terminal. The subscriber identifier
is configured to identify whether or not the mobile communication
terminal is allowed to utilize the second communication system.

[0011] A core network apparatus according to the third feature is provided
in a mobile communication system having a mobile communication terminal,
a first communication system, and a second communication system. The core
network apparatus comprising an allocation unit configured to allocate a
subscriber identifier to the mobile communication terminal, the
subscriber identifier being configured to identify whether or not the
mobile communication terminal is allowed to utilize the second
communication system.

[0012] A mobile communication terminal according to the fourth feature is
configured to perform communications with a first communication system
and a second communication system in a mobile communication system having
the first communication system and the second communication system. The
mobile communication terminal comprising a transmission unit configured
to configure a subscriber identifier to identify whether or not the
mobile communication terminal is allowed to utilize the second
communication system, and to transmit a radio signal in which the
subscriber identifier is set to the first communication system.

[0013] A mobile communication terminal according to the fifth feature is
capable of performing communications with a first communication system
and a second communication system in a mobile communication system having
the first communication system and the second communication system. The
mobile communication terminal comprising a setting unit configured that
the setting unit does not set information indicating capability to
support the second communication system in a radio signal to be
transmitted from the mobile communication terminal to the first
communication system, when the mobile communication terminal is
restricted from utilizing the second communication system, and the
setting unit sets the information indicating the capability to support
the second communication system in the radio signal to be transmitted
from the mobile communication terminal to the first communication system,
when the mobile communication system is not restricted from utilizing the
second communication system.

[0014] A mobile communication method according to the sixth feature is for
a mobile communication terminal to perform communications with a first
communication system and a second communication system. The mobile
communication method comprising a step of causing the first communication
system to determine whether or not to provide information that instructs
the mobile communication terminal to connect to the second communication
system, based on a subscriber identifier allocated to the mobile
communication terminal. The subscriber identifier is configured to
identify whether or not the mobile communication terminal is allowed to
utilize the second communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a view showing a mobile communication system 100
according to a first embodiment.

[0016]FIG. 2 is a view showing a core network apparatus 20 according to
the first embodiment.

[0017]FIG. 3 is a view for explaining a subscriber identifier according
to the first embodiment.

[0018]FIG. 4 is a view for explaining the subscriber identifier according
to the first embodiment.

[0019]FIG. 5 is a view showing a radio control apparatus 30 according to
the first embodiment.

[0020]FIG. 6 is a view showing an UE 10 according to the first
embodiment.

[0021]FIG. 7 is a sequence diagram showing operation of the mobile
communication system 100 according to the first embodiment.

MODES FOR CARRYING OUT THE INVENTION

[0022] A mobile communication system according to embodiments of the
present invention will be described hereinafter with reference to the
drawings. Note that, a same or similar symbol is assigned to a same or
similar part in the following description of the drawings.

[0023] It should be noted however that the drawings are schematic, and
that a proportion of each dimension and the like differs from an actual
one. Therefore, specific dimensions and the like should be determined by
considering the following description. In addition, it is needless to say
that drawings mutually include any different dimensional relationship or
proportion from each other.

Overview of Embodiment

[0024] First, a mobile communication system according to embodiments has a
mobile communication terminal, a first communication system, and a second
communication system. The first communication system is configured to
determine whether or not to provide information that instructs the mobile
communication terminal to connect to the second communication system,
based on a subscriber identifier allocated to the mobile communication
terminal. The subscriber identifier is configured to identify whether or
not the mobile communication terminal is allowed to utilize the second
communication system, specifically, whether or not there is any contract
(contract with a communication carrier) made for the mobile communication
terminal to utilize the second communication system.

[0026] According to the embodiment, the subscriber identifier is
configured to identify whether or not there is any contract made to
utilize the second communication system. In addition, the first
communication system determines whether or not to provide information
that instructs the mobile communication terminal to connect to the second
communication system, based on the subscriber identifier allocated to the
mobile communication terminal. Therefore, repetition of a connection
procedure to the second communication system due to absence of a contract
made to utilize the second communication system is suppressed.

[0027] Secondly, in a mobile communication system having a first
communication system and a second communication system, a mobile
communication terminal is configured to be capable of communicating with
the first communication system and the second communication system. The
mobile communication terminal includes a setting unit configured that:
the setting unit does not set information indicating capability to
support the second communication system in a radio signal to be
transmitted from the mobile communication terminal to the first
communication system when the mobile communication terminal is restricted
from utilizing the second communication system, specifically, when the
mobile communication terminal has no contract made to utilize the second
communication system; and the setting unit sets the information
indicating the capability to support the second communication system in
the radio signal to be transmitted from the mobile communication terminal
to the first communication system when the mobile communication terminal
is not restricted from utilizing the second communication system,
specifically, when the mobile communication terminal has an contract made
to utilize the second communication system.

[0028] According to the embodiment, the mobile communication terminal
switches whether or not to set the information indicating the capability
to support the second communication system in a radio signal to be
transmitted from the mobile communication terminal to the first
communication system, depending on whether or not there is a contract
made to utilize the second communication system. Therefore, repetition of
a connection procedure to the second communication system due to absence
of a contract made to utilize the second communication system is
suppressed.

First Embodiment

(Configuration of Mobile Communication System)

[0029] A configuration of a mobile communication system according to a
first embodiment will be described hereinafter with reference to the
drawings. FIG. 1 is a view showing a mobile communication system 100
according to the first embodiment.

[0030] As shown in FIG. 1, the mobile communication system 100 includes a
communication terminal apparatus 10 (hereinafter referred to as UE 10)
and a core network 50. The mobile communication system also includes a
first communication system and a second communication system.

[0031] The first communication system is a communication system supporting
UMTS (Universal Mobile Telecommunication System), for example. The first
communication system has a base station 110 (hereinafter referred to as
NB 110), an RNC 120, and an SGSN 130. Note that, a first RAT (Radio
Access Technology) is used in the first communication system.

[0032] The second communication system is a communication system
supporting LTE (Long Term Evolution), for example. The second
communication system has a base station 210 (hereinafter referred to as
eNB 210) and an MME 230, for example. Note that, in the second
communication system, a second RAT (Radio Access Technology) is used.

[0033] The UE 10 is an apparatus (User Equipment) configured to perform
communications with the first communication system and the second
communication system. For example, the UE 10 has a function to perform
radio communications with the eNB 210 as well as a function to perform
radio communications with the NB 110.

[0034] The NB 110 has a cell 111, and is an apparatus (NodeB) configured
to perform radio communications with the UE 10 existing in the cell 111.

[0035] The RNC 120 is connected to the NB 110, and is an apparatus (Radio
Network Controller) configured to set radio communications (RRC
Connection) with the UE 10 existing in the cell 111.

[0036] The SGSN 130 is an apparatus (Serving GPRS Support Node) configured
to exchange packets in a packet switching domain. The SGSN is provided in
the core network 50. An apparatus (MSC: Mobile Switching Center)
configured to switch circuits in a circuit switching domain may also be
provided in the core network 50, although it is omitted in FIG. 1.

[0037] The eNB 210 has a cell 211, and is an apparatus (evolved NodeB)
configured to perform radio communications with the UE 10 existing in the
cell 211.

[0038] The MME 230 is an apparatus (Mobility Management Entity) configured
to manage mobility of the UE 10, which sets radio communication with the
eNB 210. The MME 230 is provided in the core network 50.

[0039] Note that, it should be appreciated that a cell is a function to
perform radio communications with the UE 10. However, a cell may also be
considered a service area showing a range in which communications with
the cell is enabled. A cell is identified by frequency, a diffusion code,
or a time slot and the like to be used in the cell.

(Configuration of Core Network Apparatus)

[0040] A core network apparatus according to the first embodiment will be
described hereinafter with reference to the drawings. FIG. 2 is a view
showing a core network apparatus 20 according to the first embodiment.

[0041] The core network apparatus 20 is an apparatus to be provided in the
core network 50. In the first embodiment, the core network apparatus 20
is the SGSN 130, for example. As shown in FIG. 2, the core network
apparatus 20 has a communication unit 21 and an allocation unit 22.

[0042] The communication unit 21 performs communications with other
apparatuses (UE 10, for example). For example, the communication unit 21
notifies the UE 10 of the subscriber identifier to be allocated to the UE
10 by the allocation unit 22 to be described below.

[0043] The allocation unit 22 allocates the subscriber identifier to be
used in the first communication system, to the UE 10. The subscriber
identifier is TMSI (Temporary Mobile Subscriber Identity) or p-TMSI
(packet Temporary Mobile Subscriber Identity), for example.

[0044] Now, the subscriber identifier is configured to be capable of
identifying whether or not the mobile communication terminal is allowed
to utilize the second communication system, specifically, whether the UE
10 has a contract made to utilize the second communication system. Note
that, although an contract to utilize the second communication system is
generally made between the user of the UE 10 and the communication
carrier providing communication service by the mobile communication
system 100, identification of "whether or not the mobile communication
terminal is allowed to utilize the second communication system" is not
limited to such an contract, and also includes a case in which the
communication carrier sets an authorization to utilize the second
communication system for a specific UE 10.

[0045] In a first example, as shown in FIG. 3, a bit string of the
subscriber identifier (length of the bit string is 32 bits, for example)
includes a specific bit string indicating whether or not the UE 10 has an
contract made to utilize the second communication system. Note that, it
is preferable that the specific bit string is provided at the head of the
bit string of the subscriber identifier.

[0046] If the UE 10 has the contract made to utilize the second
communication system, the allocation unit 22 allocates the subscriber
identifier including a specific bit string indicating accordingly, to the
UE 10. On the one hand, if the UE 10 has no contract made to utilize the
second communication system, the allocation unit 22 allocates the
subscriber identifier including a specific bit string indicating
accordingly, to the UE 10.

[0047] In a second example, as shown in FIG. 4, an identifier space of the
subscriber identifier that can be allocated to the UE 10 in the first
communication system includes an identifier space of the subscriber
identifier to be allocated to the UE 10 having an contract made to
utilize the second communication system (with an contract) and the
identifier space of the subscriber identifier to be allocated to the UE
10 having no contract made to utilize the second communication system
(with no contract).

[0048] If the UE 10 has a contract made to utilize the second
communication system, the allocation unit 22 allocates the subscriber
identifier to the UE 10 from the identifier space of the subscriber
identifier (with a contract). On the one hand, if the UE 10 has no
contract made to utilize the second communication system, the allocation
unit 22 allocates the subscriber identifier from the identifier space
(with no contract) of the subscriber identifier.

(Configuration of Radio Control Apparatus)

[0049] A configuration of the radio control apparatus according to the
first embodiment will be described hereinafter with reference to the
drawings. FIG. 5 is a view showing the radio control apparatus 30
according to the first embodiment.

[0050] In the first embodiment, the radio control apparatus 30 is provided
in the first communication system. The radio control apparatus is the RNC
120, for example.

[0051] As shown in FIG. 5, the radio control apparatus 30 has a
communication unit 31 and a determination unit 32.

[0052] The communication unit 31 performs communications with other
apparatuses (UE10, for example). The communication unit 31 receives a
radio signal (RRC CONNECTION REQUEST, for example) from the UE 10. In
addition, the communication unit 30 transmits a radio signal (RRC
CONNECTION REJECT, for example) to the UE 10.

[0053] Now, the subscriber identifier to be allocated by the core network
apparatus 20 is set in "RRC CONNECTION REQUEST" to be transmitted from
the UE 10 to the radio control apparatus 30. Information (pre-redirection
info) indicating capability to support the second communication system
may also be set in "RRC CONNECTION REQUEST."

[0054] In addition, "RRC CONNECTION REJECT" to be transmitted from the
radio control apparatus 30 to the UE 10 is a radio signal to reject the
connection to the first communication system. Information (Redirection
info) that instructs the UE 10 to connect to the second communication
system (Redirection) may be set in "RRC CONNECTION REJECT" (RRC
CONNECTION REJECT with redirection).

[0055] The determination unit 32 determines whether or not to instruct the
UE 10 to connect to the second communication system (Redirection). To be
specific, the determination unit 32 determines whether or not to notify
the UE 10 of information (Redirection info) that instructs the UE 10 to
connect to the second communication system (Redirection), based on the
subscriber identifier allocated to the UE 10.

[0056] More specifically, if the UE 10 has a contract made to utilize the
second communication system, the determination unit 32 determines to set
the information (Redirection info) that instructs the UE 10 to connect to
the second communication system (Redirection) in a radio signal (RRC
CONNECTION REJECT). On the one hand, if the UE 10 has no contract made to
utilize the second communication system, the determination unit 32
determines not to set the information (Redirection info) that instructs
the UE 10 to connect to the second communication system (Redirection) in
a radio signal (RRC CONNECTION REJECT).

[0057] Note that, the determination unit 32 determines whether or not to
provide notification of the information (Redirection info) that instructs
the UE 10 to connect to the second communication system, based on the
information (pre-redirection info) indicating the capability to the
second communication system.

[0058] Particularly, if the UE 10 has the capability to support the second
communication system, the determination unit 32 determines to set the
information (Redirection info) that instructs the UE 10 to connect to the
second communication system (Redirection) in the radio signal (RRC
CONNECTION REJECT). On the one hand, if the UE 10 has no capability to
support the second communication system, the determination unit 32
determines not to set the information (Redirection info) that instructs
the UE 10 to connect to the second communication system (Redirection) in
the radio signal (RRC CONNECTION REJECT).

[0059] Specifically, if the UE 10 has the contract made to utilize the
second communication system and the capability to support the second
communication system, the determination unit 32 determines to instruct
the UE 10 to connect to the second communication system (Redirection).

(Configuration of Mobile Communication Terminal)

[0060] A configuration of the mobile communication terminal according to
the first embodiment will be described hereinafter with reference to the
drawings. FIG. 6 is a view showing the UE 10 according to the first
embodiment. As shown in FIG. 6, the UE 10 has a communication unit 11 and
a setting unit 12.

[0061] The communication unit 11 performs radio communications with the NB
110. The communication unit 11 also performs radio communications with
the eNB 210. The communication unit 11 transmits a radio signal (RRC
CONNECTION REQUEST, for example). The communication unit 11 receives a
radio signal (RRC CONNECTION REJECT, for example).

[0062] The setting unit 12 sets information (pre-redirection info)
indicating capability to support the second communication system in "RRC
CONNECTION REQUEST."

[0063] Particularly, if the UE 10 has a contract made to utilize the
second communication system, the setting unit 12 sets information
indicating the capability to support the second communication system in
"RRC CONNECTION REQUEST." On the one hand, if the UE 10 has no contract
made to utilize the second communication system, the setting unit 12 does
not set the information (pre-redirection info) to support the second
communication system in "RRC CONNECTION REQUEST."

[0064] Note that, the UE 10 manages whether or not the UE 10 has a
contract made to utilize the second communication system.

[0065] It should be noted that, if the UE 10 determines whether or not to
set the information (pre-redirection info) indicating the capability to
support the second communication system in "RRC CONNECTION REQUEST," the
core network apparatus 20 described above does not need to allocate the
subscriber identifier to the UE 10, depending on whether or not there is
an contract made to utilize the second communication system.

(Operation of Mobile Communication System)

[0066] The operation of the mobile communication system according to the
first embodiment will be described hereinafter with reference to the
drawings. FIG. 7 is a sequence diagram showing the operation of the
mobile communication system 100 according to the first embodiment. Now,
the case in which the radio control apparatus 30 is the RNC 120 will be
exemplified.

[0067] As shown in FIG. 7, in step S10, the UE 10 is in standby state
"IDLE."

[0068] In step 20, the UE 10 transmits to the RNC 120 a radio signal (RRC
CONNECTION REQUEST) to request setting of radio connections. Now, the
subscriber identifier is set in "RRC CONNECTION REQUEST." In addition, in
the first embodiment, information (pre-redirection info) indicating
capability to support the second communication system is set in "RRC
CONNECTION REQUEST."

[0069] In step 30 the RNC 120 determines whether or not to instruct the UE
10 to connect to the second communication system (Redirection), based on
information (subscriber identifier, "pre-redirection info") set in "RRC
CONNECTION REQUEST." Specifically, if the UE 10 has a contract made to
utilize the second communication system and the capability to support the
second communication system, the RNC 120 determines to instruct the UE 10
to connect to the second communication system (Redirection).

[0070] Note that, in the following, a description will be continued,
assuming that the RNC 120 determined to instruct the UE 10 to connect to
the second communication system (Redirection).

[0071] In step 40, the RNC 120 transmits to the UE 10 a radio signal (RRC
CONNECTION REJECT with redirection) in which the information instructing
the connection to the second communication system (Redirection) is set.

[0072] In step 50, the UE 10 selects a cell. To be specific, the UE 10
selects a cell provided in the second communication system, using the
information (Redirection info) instructing the connection to the second
communication system (Redirection).

[0073] In step 60, the UE 10 transmits to the eNB 210 a radio signal (RRC
CONNECTION REQUEST) to request setting of radio communications.

(Operation and Effect)

[0074] First, in the first embodiment, the subscriber identifier (TMSI or
p-TMSI, for example) is configured to identify whether or not there is
any contract made to utilize the second communication system. In
addition, the radio control apparatus 30 provided in the first
communication system determines whether or not to provide information
(Redirection info) that instructs the mobile communication terminal to
connect to the second communication system, based on the subscriber
identifier allocated to the UE 10. Therefore, repetition (ping pong
phenomenon) of a connection procedure to the second communication system
due to absence of a contract made to utilize the second communication
system is suppressed.

[0075] Secondly, in the second embodiment, depending on whether there is
any contract made to utilize the second communication system, the UE 10
switches setting or not setting of information indicating capability to
support the second communication system, in a radio signal to be
transmitted from the UE 10 to the first communication system. Therefore,
repetition (ping pong phenomenon) of the connection procedure to the
second communication system due to absence of the contract made to
utilize the second communication system is suppressed.

Other Embodiments

[0076] Although the present invention has been described with the
embodiments mentioned above, statement and drawings which form a part of
the disclosure should not interpreted as limiting the present invention.
From the disclosure, various alternative embodiments, embodiments and
operating technologies will be apparent to those skilled in the art.

[0077] In the embodiments described above, the first communication system
is a communication system supporting UMTS, and the second communication
system is a communication system supporting LTE. Specifically, the
connection to LTE (Redirection) has been described. However, the
embodiments are not limited to this. To be specific, the first
communication system may be a communication system supporting LTE, and
the second communication system may be a communication system supporting
UMTS. Specifically, it may be applied to connections (Redirection) to
UMTS.

[0078] In addition, the first communication system and the second
communication system are not limited to the communication system
supporting UMTS or LTE, and may be any other communication system
(communication system supporting WiMAX, for example).

[0079] In the embodiments described above, as the subscriber identifier,
TMSI or p-TMSI to be allocated to the UE 10 by the core network apparatus
20 is exemplified. However, the subscriber identifier may be a subscriber
identifier which cannot be allocated to the UE 10 by the core network
apparatus 20, such as IMSI (International Mobile Subscriber Identity) and
the like.

[0080] In the embodiments described above, although the case in which the
core network apparatus 20 was the SGSN 130 was exemplified, the
embodiment is not limited to this. The core network apparatus 20 maybe an
apparatus to be provided in the core network 50.

[0081] In the embodiments described above, although the case in which the
radio control apparatus 30 is the RNC 120 was exemplified, the embodiment
is not limited to this. The radio control apparatus 30 may be an
apparatus which is provided in RAN (Radio Access Network) provided in the
first communication system.

[0082] In the embodiment described above, although no special mention was
made, the UE 10 may be configured to make the subscriber identifier so as
to identify whether or not there is any contract made to utilize the
second communication system, and transmit to the first communication
system a radio signal ("RRC CONNECTION REQUEST, " for example) in which
the subscriber identifier is set. The UE 10 may be configured to convert
the subscriber identifier (TMSI or p-TMSI) allocated by the core network
50 into the subscriber identifier made to identify whether or not there
is any contract made to utilize the second communication system, for
example. The UE 10 temporarily converts the subscriber identifier when
transmitting "RRC CONNECTION REQUEST," for example.

[0083] In the embodiments described above, the radio control apparatus 30
determines whether or not to instruct the mobile communication terminal
to connect to the second communication system, when the first
communication system transmits "RRC CONNECTION REJECT" to the UE 10.
However, the embodiment is not limited to this.

[0084] To be specific, if the UE 10 is in communication with the first
communication system, the radio control apparatus 30 may determine
whether or not to instruct the mobile communication terminal to connect
to the second communication system, based on the subscriber identifier
allocated to the UE 10. For example, the radio control apparatus 30 may
set information that instructs the mobile communication terminal to
connect to the second communication system, in a radio signal "RRC
CONNECTION RELEASE" to release the radio resource of the first
communication system. Alternatively, the radio control apparatus 30 may
determine whether or not to notify the UE 10 of information that
instructs the mobile communication terminal to connect to the second
communication system, in handover (Inter-RAT Handover) procedure from the
first communication system to the second communication system.

[0085] Although no special mention was made in the embodiments described
above, allocation of the subscriber identifier according to the
embodiment may be used to identify a test terminal prior to development
into commercial use. Specifically, the test terminal prior to development
into commercial use may be handled as the UE 10 having a contract made to
utilize the second communication system.

[0086] Note that, the operation of the UE 10 described above may be
implemented by hardware or a software module which is executed by a
processor, or by a combination thereof.

[0087] The software module may be provided in a storage medium of any
format such as a RAM (Random Access Memory), a flash memory, a ROM (Read
Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM
(Electronically Erasable and Programmable ROM), a register, a hard disk,
a removable disk, or a CD-ROM.

[0088] The storage medium is connected to a processor so that the
processor can read and write information from/into the storage medium. In
addition, the storage medium may be integrated in the processor.
Furthermore, the storage medium and processor may be provided in an ASIC.
The ASIC may be provided in the UE 10. In addition, the storage medium
and processor may be provided in the UE 10 as a discrete component.

[0090] With the present invention, a mobile communication system, a radio
control apparatus, a core network apparatus, a mobile communication
terminal, and a mobile communication method which can suppress repetition
of a connection procedure to a second communication system can be
provided. Therefore, the present invention is useful in radio
communications and the like.